The present invention relates to improvements in winders, particularly the type for winding a continuous web, such as of paper, onto a roll.
The invention relates to an improvement in a winding and reeling machine and one which is particularly successful in starting the lead end of a web onto a core. In a reeling or winding machine for continuously winding web material without interruption on successive drum supported cores, it is necessary at the completion of the winding of one roll to provide a roll changing device which will positively transfer the web onto a new roll. A new roll is started by cutting the tail end of the web from the previous roll and guiding or leading the cut end onto a core to start the new roll. This is done by a portion of the web being directed into a nip point created usually between a lay-on roll and a new core.
Typical web transferring devices that operate on a core-supported wind-up without interruption of the web rely on air jets or tape to separate the sheet from the drum onto the new core. Air jet transfers frequently produce unkept transfers inasmuch as wrinkles and fold-overs form in the unsupported web before completing the initial wrap. These, of course, will affect successive layers generating an uneven start to the new roll.
In the use of tape, tension by an operator is necessary, and this method is frequently unsafe and often will contaminate the mill repulping system with non-repulpable tape getting into the system. The tape arrangement also produces conical shaped rolls because it utilizes a web winding widening technique for starting the web onto the new core. Both the air transfer and the tape transfer methods are detrimental to the roll structure near the core.
Non-uniformities in diameter adversely affect the use of nip pressure to produce uniform cross-machine wound-in tension. Layers on a roll which are wrapped with different tension levels produce web defects often in the nature of corrugations. Also, circumferential web tension produced near the core is reduced as subsequent web wraps are introduced onto the roll. It is critical that the initial wraps are wound tightly enough to remain in tension and prevent layer-to-layer slippages as the roll builds. Improper or unsatisfactory winding on the core with the initial start minimizes salable web material. Also, if a transfer onto the core is missed, the high speed of operation results in a gigantic pile-up of paper which is waste and must be transferred to the broke, and expensive shut-down time occurs. When the transfer is made successfully, but the initial winding is improper because of improper tension or because of corrugations, it is common experience that the first two to five radial inches of material must be scrapped by the user due to web defects caused by sloppy transfers. Transfer efficiency in devices presently available is often less than 90%.
It is, accordingly, an object of the present invention to provide a roll changing device and method which will positively transfer the web onto a new roll avoiding failures in transfer and avoiding inadequate transfer which damages the paper on the initial winding of web onto a roll.
A further object of the invention is to provide a web winding transfer apparatus for starting a web on a core that insures a smooth and complete first wrap with the wrapping continuing around the core without wrinkles and corrugations and at uniform desired web tension.
A still further object of the invention is to provide an improved reeling or winding machine with improved web control wherein the initial lay-on of the web on a new core is carried out smoothly and control of the new winding roll is continued.